@LTU_btc suggests to just accept the QR society and buy a code on the black market.
Well, I didn't said that. My thought is that if governments will make vaccination mandatory, black market for vaccine passpprts will be big. It's difficult to expect that even with mandatory vaccination 100% of people will take vaccine. Even now some are trying to get fake passports.
Yeah sorry, my summary wasn't exactly what you said. Would you accept a QR society, assuming you can get all the fake passports you need?